1. Field of Invention
This invention relates to a sea-floor template for the drilling of boreholes or installing piles in the ocean floor. It relates especially to a floating template that has scissored arms with flotation means for ease of transportation.
In recent years there has been considerable attention attracted to the drilling and production of wells located in water. Wells may be drilled in the ocean floor from either fixed platforms in relatively shallow water or from floating structures and vessels in deep water. The most common means of anchoring fixed platforms includes the driving or otherwise anchoring of long piles in the ocean floor. Such piles normally extend above the surface of the water and support platforms attached to the top of the pile. This works fairly well in shallow waters, but as the water gets deeper the problems of design and accompanying cost become prohibitive. In deeper water, it is common practice to drill from floating structures.
In recent years there has been considerable attention directed toward many different kinds of floating structures. One system receiving attention is the so-called Vertically Moored Platform. Such a platform is described in U.S. Pat. No. 3,648,638, issued Mar. 14, 1972, Kenneth A. Blenkarn, inventor. A chief feature of the disclosure in that patent is that the floating platform is connected to an anchor only by elongated parallel members and the floating structure has buoyancy means designed especially with respect to the trough of the design wave so as to minimize variations in vertical forces imposed on the vertically elongated members which may be caused by passing waves. There are other types of floating drilling vessels, such as the semisubmersible and the floating drilling vessel with a moonpool or vertical opening through the center through which drilling operations are carried out. The drilling engineer selects a floating vessel which he believes will best fit the environmental conditions which are expected to be encountered. A typical subsea floor well pattern for a Vertically Moored Platform is a group of eight wells in a circular pattern at each corner of a square. The template of the present invention can be used to establish such a pattern.
2. Prior Art
The closest prior art relating to our invention, to the best of our knowledge, concerns templates or frames on the ocean floor having a vertical passage through which a well may be drilled. The prior art template would be fabricated in a fabrication yard as a fixed structure. It would be transported to a well site at the selected marine location and lowered to the sea floor. None of the prior art of which we are aware has a template composed of scissor-like arms pivoted about a scissor pivot.